The recent release of QGIS 1.0 provides an excellent opportunity for developers looking to create standalone mapping applications with Python.
I recently posted an article on creating a very simple standalone application with Python and QGIS 1.0. Much of the Python efforts thus far have been devoted to creating QGIS plugins. I think now that we have a stable API, you'll begin to see more custom applications that meet a specialized need.
If you are developing such applications, it would be great to hear from you.